Cathode ray tube



April 2, 1940. o. BAIER CATHODE RAY TUBE Filed Feb. 25, 1938 fzzwzzz br: 0170 Ba/Zer 5y W "Ji'hrney Patented Apr. 2, 1940 i UNITED STATES PATENT; OFFICE OATHOD-E RAY TUBE Otto Baier, Berlin, Germany,v assignor to C.

Lorenz Aktiengesellschaft, Berlin-Tempe1hof, Germany, a company I Application February 23, 1938, Serial No. 192,047 In Germany February 22, 1937 4 Claims. (Cl.250-'-141) (Granted under the provisions of sec. 14, act of March 2, 1927; 357 O; G. 5)

The present invention relates to cathode ray compulsorily secure a'given position of the electubes, and particularly to improvements with tron emitting surface 4 with respect to the base respect to the supporting meansforthe cathode surface of the insulating body I. The lower end and the control electrode of such tubes. of the nickel tube is turned over the bottom sur- 1 The relative adjustment of the. cathodev and face of the insulating body I in order to secure the control electrode is of utmost importance in rigid connection. The cathode is heated by making cathode ray. tubes, since the correct dismeans of a heating coil. One of the cathode tance between the glowing cathode and the conleads 3 is placed within the nickel tube, while trol electrode or Wehnelt cylinder determines the the second lead 3 extends through a particular characteristic of the tube. In serially manuhole 5 provided in theinsulating body I. The 10 facturing cathode ray tubes particularly for teleupper portion of the insulating body I is. provision purposes, it is most desirable that each vided with a groove which serves as a seat for at individual tube has substantially the same charmetal cap 6. The position of this metal cap with acteristic. The known constructions of cathode respect to e emitting surface of the cathode is 15 ray tubes having a glowing cathode are rather thus given by said groove, so that there is no disadvantageous in this respect. The physical necessity for any kind of adjustment of this disuppcrt of the cathode generally consists of one tance which is most'significant for the tube charsingle lug which simultaneously acts as lead-in acteristic. The outer surface of the insulating conductor. It has, therefore, been necessary in body car s a longitudinal slot '1 throu h Which i each case to subject the cathode to special ada lug 3 0f the p 9 is extended the lower end justment, a requirement which has not been of the body I. This body together with the oath-'- conducive to facilitate the manufacturing proc- Ode 2 an t e co t ol electrode 5 s i d n ess. In addition, this type of support suffers unpress fi hi n in a holding m r l cated der a considerable lack of stability and is, therein he Center Of t electrode system- O y the fore, subjected to changes on heating the tube, ess parts of this system, e pp g 25 or under the influence of mechanical vibrations. rods 9, e concentrating cylinder ID with its dia- These disadvantages are obviated according to ph a indicated in The d n the present invention which proposes the cathode m r s shown s a hollow y de H which to be fixedly mounted in a supporting member, is fixed t0 t e electrode system y clamp rings, whereupon this combined body is attached in a f amp r y a s f a num er of discs press fit fashion to a hollow cylinder mounted l3 s shown in s0 as to Obtain concentric in the center of the electrode system of the tube. position thereof W respect to e ap m The invention will be more readily understood II. The coaxial relation of the cathode 2 and from the following description taken in com the diaphragm M of the control electrode 6 to the junction with the accompanying drawing, in lens diaphragm H and the metal cylinder I2 is whi hthus compulsorily given, so that merely an axial Fig. 1 shows a cross section through a new elecadjustment is q eds djustment is actrode assembly according to the invention; Fig. 2 p d by the agency of the 111g 3 Which is is a bottom view of the arrangement shown i bent over the cylinder l2'and attached to the disc Fig. 1; while Fig. 3 illustrates a cross section 13 by di for example s a ement through a further modification of the inventive v d s reliable Contact between the n and idea thecylinder [2, so that the effective area of the Referring to Figs. 1 and 2, reference numeral 1 control electrode is still increased by the hollow indicates an insulating body, e. g., of a ceramic cylinder I2. material. This body has a central bore, the A further modification of the inventive idea is upper portion of which is flared. The cathode 2, shown in Fig. 3. The cathode 2 is carried by an which in this embodiment is assumed to be a insulating tube I5 through which the two lead-in small nickel tube, the upper end of which is conductors 3 extend. The insulating tube I5 is closed so as to form a surface for the electron placed in a support I of very low heat conductiv- 50 emitting substance, while its lower end presents ity, e. g., Invar steel. This support is provided reduced diameter by me s of a o c Po t o with a shoulder It. A disc-shaped diaphragm I1 is inserted into the bore of the insulating body I. which is mounted in any manner in the center The flared portion of this body serves as a seat of the electrode system carries a hollow cylinder for the conical portion of the cathode 2, so as to I8 attached to its lower face by welding, for in- 68 stance. This hollow cylinder is adapted to receive the metallic support I and the cathode 2 attached thereto. On inserting the last mentioned unit, the shoulder l6 serves as a detent so as to secure a predetermined axial interspace between the emitting face of the cathode and the adjacent electrode thereof. The hollow cylinder l8 and the disc-shaped diaphragm l'l conjointly serve as control electrode or Wehnelt cylinder. In contradiction to the first embodiment, this modification employs a supporting member which is maintained at the same potential as the control electrode from which follows that the cathode must be insulated from the metallic support I.

Referring for instance to the arrangement first described, the cap of the control electrode'may be fixed to the open ended hollow cylinder carrying the insulating body, instead of being fixed to this body. On the other hand the reverse of the above mentioned possibility maybe applied to-theisecond modification, that is to say to,provide the metallic support with a capand to enlarge thediaphragm of the disc l1. It is thus obviousthat the invention is by no means limited to the structures heretofore describedand'demonstrated merely by way of examples.

Thecathodethusshown is unmovably fixed in a supporting member which is in turn inserted in a hollowcylinder fixed in thecenterof the electrode system. A structure of perfect stability is thereby obtained, so-that the cathode will remain unaffected by whatever vibrations may occur. Since the cathode is mounted in a supporting member located externally with respect to the electrode system, the above mentioned adjusting process becomes very simple, so that noexpertness is required for accomplishing this adjustment. In cases of a repair, a damaged cathode may easilybe replaced by another cathode merely byremoving the supporting member.

What is claimed is:

1. A cathode ray tube comprising a cathode, a

supporting means of insulating material therefor, a hollow cylinder in which said supporting means is slidably positioned, said cylinder being of such diameter as frictionally to hold said supporting means, whereby the position of said cathode with respect to said cylinder may be readily adjusted, a diaphragm electrode carried by said supporting means in fixed spaced relation with respect to said cathode so as to move with said cathode upon adjustment of the position thereof, and additional electrodes coaxial with said hollow cylinder and supported conjointly therewith.

2. A cathode ray tube in accordance with claim 1, wherein said hollow cylinder is fixed to supporting discs carried by supporting rods which serve to align the cathode with respect to other electrodes of the tube.

3. A cathode ray tube in accordance with claim 1, wherein said cylinder is carried by a disc and said diaphragm electrode has a deformable lug which is bent in the form of aloop and attached to said disc tohold said electrode against displacement, the size of said loop being suificient to permit longitudinal adjustment of said insulating supporting means within said hollow cylinder.

4. A cathode ray tube comprising a body of insulating imaterial having a metallic tube centrally positioned therein, a heating coil positioned within said tube, a closure for the end of said tube forming an emitting surface, said body of insulating material having a recess forming an opening around said middle tube, and a control electrode comprising a metallic diaphragm having a central opening therein supported by the end of said insulating body and a hollow cylinder slidably enclosing said insulating body in tight frictional engagement to hold said body in a fixed position.

O'I'IO BAIER. 

